This is a note to let you know that I've just added the patch titled
persistent_ram: Fix buffer size clamping during writes
to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also will be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From 484dd30e016eb425b0de871357fff2c9bb93be45 Mon Sep 17 00:00:00 2001
From: Anton Vorontsov <[email protected]>
Date: Fri, 11 May 2012 17:17:17 -0700
Subject: persistent_ram: Fix buffer size clamping during writes
This is a longstanding bug, almost unnoticeable when calling
persistent_ram_write() for small buffers.
But when called for large data buffers, the write routine behaves
incorrectly, as the size may never update: instead of clamping
the size to the maximum buffer size, buffer_size_add_clamp() returns
an error (which is never checked by the write routine, btw).
To fix this, we now use buffer_size_add() that actually clamps the
size to the max value.
Also remove buffer_size_add_clamp(), it is no longer needed.
Signed-off-by: Anton Vorontsov <[email protected]>
Acked-by: Colin Cross <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/staging/android/persistent_ram.c | 19 +------------------
1 file changed, 1 insertion(+), 18 deletions(-)
diff --git a/drivers/staging/android/persistent_ram.c
b/drivers/staging/android/persistent_ram.c
index 12444fd..13a12bc 100644
--- a/drivers/staging/android/persistent_ram.c
+++ b/drivers/staging/android/persistent_ram.c
@@ -79,23 +79,6 @@ static inline void buffer_size_add(struct
persistent_ram_zone *prz, size_t a)
} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
}
-/* increase the size counter, retuning an error if it hits the max size */
-static inline ssize_t buffer_size_add_clamp(struct persistent_ram_zone *prz,
- size_t a)
-{
- size_t old;
- size_t new;
-
- do {
- old = atomic_read(&prz->buffer->size);
- new = old + a;
- if (new > prz->buffer_size)
- return -ENOMEM;
- } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
-
- return 0;
-}
-
static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
uint8_t *data, size_t len, uint8_t *ecc)
{
@@ -300,7 +283,7 @@ int notrace persistent_ram_write(struct persistent_ram_zone
*prz,
c = prz->buffer_size;
}
- buffer_size_add_clamp(prz, c);
+ buffer_size_add(prz, c);
start = buffer_start_add(prz, c);
--
1.7.10.1.362.g242cab3
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